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The purpose of the study is to examine the main methods of obtaining fertilizers and optimizing processes. Using methods of analysis, comparison, and experimentation, three main approaches to obtaining fertilizers were identified: grinding and mixing with potassium hydroxide (KOH), ultrafine grinding with chemical additives, and a complex method for processing caustobioliths. Comparative analysis of the investigated methods allowed for identifying their advantages, disadvantages, and effectiveness. The key result was the ability to determine the most effective method for producing humate-containing fertilizers from brown coal, depending on specific production conditions and requirements. The results of the study showed that the ultrafine grinding process with chemical additions, such as urea and alkali metal hydroxides, showed promising potential for creating highly effective humate-containing fertilizers from brown coal, in addition to the comparative analysis. After thorough optimization, this technique showed improved fertilizer utilization and superior plant uptake, making it a strong contender for sustainable farming methods. Nevertheless, achieving optimal results requires detailed process parameter optimization. The study underscores the importance of using brown coal in humate-containing fertilizer production as an environmentally safe and sustainable approach. The results can contribute to further development and improvement of humate-containing fertilizer production methods, promoting sustainable agriculture and increased crop productivity. [ABSTRACT FROM AUTHOR]

The aim of the study was to compare the effect of two leonardites (Humitec® and Humic Gold®) and an organic compost (Nutrimais®) with an untreated control on lettuce. The pot experiment was carried out in NE Portugal, in autumn 2019 and spring 2020. Humitec, Humic Gold and Nutrimais were applied alone or as a supplement to nitrogen (N), phosphorus (P) and potassium (K). The experiment was arranged as a three-factor experimental design (organic amendment, NPK addition and growing season). The growing season significantly influenced lettuce dry matter yield (DMY), the spring cycle being the highest yielding (10.6 to 6.5 g plant−1). NPK fertilization also significantly increased lettuce DMY (11.2 to 5.9 g plant−1). The organic amendment significantly influenced the concentration of some nutrients in plant tissues and some soil properties, but it did not influence lettuce DMY. In respect of growing season, Nutrimais increased lettuce DMY in the first one. In relation to the absence or otherwise of NPK fertilization, Nutrimais increased lettuce DMY in the pots not receiving NPK. Leonardites did not influence soil properties, tissue nutrient concentration or lettuce DMY. The positive effect on the lettuce DMY of organic compost was probably due to the supply of N, apparently the plants' most significant limiting factor. The non-positive results of leonardites were due to the fact that they neither provided N, nor enhanced its bioavailability from the soil. Thus, NPK fertilizer and Nutrimais, a compost of low C/N ratio, providing some N had the greatest effect on lettuce DMY. [ABSTRACT FROM AUTHOR]

Improved predictability of the effectiveness of biostimulant products is required before their wider acceptance by ornamental plant growers. We investigated the effects of three of the main groups of biostimulants (humic acids, protein hydrolysates, and seaweed extracts) under six fertilization levels, using Antirrhinum majus L. as a model ornamental plant to evaluate potential interactive effects on plant performance and growth substrate biological activity. Number of leaves increased in response to biostimulant application, but leaf area was generally reduced, especially in potting mix with lower fertility. Seaweed extract had beneficial effects on both shoot and root dry mass accumulation but was less beneficial than higher fertilizer rates. The beneficial effects of protein hydrolysates and humic acids were marginal and less predictable under our experimental conditions; humic acids showed particularly negative effects on root dry mass accumulation. All biostimulants showed negative impacts on substrate microbial activity, although Dehydrogenase Activity (DHA) was substantially higher under lower fertility. Extrapolation of the results of this study suggests that it is feasible to apply biostimulants, particularly seaweed extracts, to improve the overall growth performance of ornamental plants. However, it is essential to consider the nutrient status of growth medium if we are to leverage the biostimulant paradigm in the ornamental plant sector. [ABSTRACT FROM AUTHOR]

Soil organic matter (SOM) is the most important factor that affects soil quality. In arid areas, lack of SOM causes a major problem and farmers need to add organic amendments to restore the soil quality. Organic waste composting is an efficient and sustainable way to produce organic resource for soil amendment. The main objective of this study was to evaluate the effectiveness of compost derived from co-composting of date palm residues with goat manure to ameliorate soil quality in arid region in the southeast of Tunisia. Palm tree wastes were co-composted with goat manure (1/3 v:v) for 120 days. Chemical properties and structural changes of humic acids (HA) during the composting process were investigated using physicochemical and spectroscopic analyses: spectroscopic ultraviolet/visible (UV) analysis and Fourier Transform Infrared (FTIR) Spectroscopy. HA fractions extracted from different steps of composting process were monitored by measuring humification ratios CHA/CFA and E4/E6. Soil was amended with produced compost and manure during 3 months, and soil property evolution was evaluated using chemical and spectroscopic analyses. Results revealed that the date palm compost displayed neutral pH, a C/N ratio of about 12 and high levels of nutrients. FTIR spectra of HA extracted from produced compost and manure showed the abundance of aromatic structures with a high condensation and polymerization confirmed by a low E4/E6 ratio related to the increase in polymerization and polycondensation and a high CHA/CFA humification rate that improved the elevation of the humification degree. The application of the produced palm compost in soil improved soil quality by increasing levels of SOM and nutrients and showed a marked improvement of humification rate. The FTIR spectra of soil HA showed a clear increase in aromatic structures that improved soil stability. The input of palm compost is an efficient way to ameliorate arid soil quality by supplying highly humified organic matter restitution. [ABSTRACT FROM AUTHOR]

Heavy metals were typical contaminants in aquatic ecosystems, while their effects on the biotoxicity and metabolism of algal cells in the presence of organic ligands were still unclear. In this study, the contrasting effects of Cu and humic acids (HA) on the growth inhibition, oxidative stress and extracellular secretion of microalga Chlorella vulgaris were studied at environmentally relevant concentrations of Cu (0~2 mg/L) and HA (0~20 mg/L). Results showed that, with increased Cu addition, the algal growth rate decreased while concentrations of superoxide dismutase and malondialdehyde increased showing evident growth inhibition and oxidative damage in the sole presence of Cu. However, the presence of HA could significantly alleviate the Cu-induced toxicity damage, and higher concentrations of HA exhibited greater alleviation efficiencies. Fluorescence spectroscopy combined with flow field flow fractionation revealed that secretion of 50 kDa~0.45 μm of extracellular protein-like substances was the critical fractions responsible for the biotoxicity alleviation. Analysis of Cu contents within extracellular polymeric substance (EPS) matrix showed that not only the secretion amounts but also the acquisition capacities of EPS matrix decreased due to the addition of HA. This study benefited an in-depth understanding toward the toxicity of heavy metals to aquatic microorganisms in natural waters that contained abundant organic ligands. [ABSTRACT FROM AUTHOR]

This paper investigates interaction processes of the Fe3+, Cu2+, Ni2+, and Co2+ cations with humic acids isolated from brown coals of Ekibastuz basin. It was demonstrated that the sorption of heavy metal ions by humic acids (HA) depends on the concentration and nature of cations and decreases in the order of Fe3+ > Cu2+ > Ni2+ > Co2+; while increase in the concentration of humic acids (HA) results in the higher yield of ions and metals. The occurrence of ion exchange and complexation reactions in metal-humic acid systems is confirmed by the appearance of new bands and the shift of the absorption bands corresponding to stretching and deformation vibrations of carboxylate ions, C = O and OH groups. The occurrence of these processes is also evidenced by spectrophotometric data, as well as a decrease in the pH of the solution due to deprotonation of humic acids during these reactions. Thus, based on the data on the degree of sorption of metal cations by humic acids, the results of infra-red spectroscopy and spectrophotometry, it can be concluded that the Fe3+, Ni2+, Co2+, Cu2+ cations interact with HA by the ionic mechanism and by the complexation mechanism with electron-donating functional groups. Electrochemical studies of the Cu2+ – humic acid system carried out by the method of cyclic voltammetry also indicate the occurrence of the interaction of humic acid with copper cations. Modification of humic acid with copper ions shows the electrochemical activity of copper immobilized on the surface of dispersed humic acid, which is important for the implementation of electrocatalytic reactions on modified glassy carbon-humic electrodes. [ABSTRACT FROM AUTHOR]

On the example of cultures of bacteria Pseudomonas sp. and Bacillus sp. the effect of humic acids in the concentration range (0–15 mg/L) on the viability of these bacteria was studied. Multidirectional effects of humic acids on microorganisms were found, namely, at concentrations of 1 and 5 mg/L, they reduce, and at 15 mg/L, they do not affect the survival of the studied cultures of bacteria. It has been established that the treatment of aqueous solutions of humic acids with a weak magnetic field affects their physicochemical properties and structural parameters, as well as enhances the biological effect in relation to different groups of microorganisms. It was established that the multidirectionality of the biological effect of humic acids on microorganisms is well explained from the position of considering humic acids as complex open non-equilibrium systems with a developed system for energy dissipation, which leads to the formation on their basis of diverse and complex self-organized structures with different physicochemical properties. The obtained concentration dependences confirm the possibility of the existence of humic acids in the studied concentration range in at least two states. Moreover, it is the state of the system (the level of self-organization), and not the relationship with the source of origin of a humic acids, mainly determines its properties. This fact determines the possibility of using the concentration of humic acids to establish the level of organization of the system, which will allow to manage the structural organization of these objects and predict their properties. [ABSTRACT FROM AUTHOR]

The thermal stabilities of humic acids (HAs) are critical for its effective utilization and relate closely with raw lignites. Thus, this work is to study the relationship of thermal stability between lignites and its derived HAs using Thermogravimetry – Fourier Transform Infrared Spectroscopy (TG-FTIR) and Differential Scanning Calorimetry Measurement (DSC) techniques. The TG-FTIR results indicated that the intensities of peaks from the evolution gases (H2O, CO2, CO, CH4) during thermal treatment of Zhaotong lignite (ZL) and its derived HAs (denoted as ZLHA) are higher compared with the Mile lignite (ML) and its derived HA (denoted as MLHA). TG-FTIR and DSC measurements of lignites showed that the thermal stability of ML is better than that of ZL, and the more oxygen containing functional groups existed in ZL. Similarly, the results indicated that the contents of oxygen containing functional groups of ZLHA are higher than that of MLHA. On the other hand, DSC experimental data showed that the MLHA has smaller peaks on the DSC profiles, which showed that MLHA has longer aliphatic chain and less oxygen containing functional groups. Briefly, the results obtained from TG-FTIR and DSC measurement are consistent. The thermal stabilities of HAs are highly associated with the physicochemical property of raw lignites. [ABSTRACT FROM AUTHOR]

The use of applied phosphorus (P) and the uptake of nutrients from the soil by plants can be improved when the fertilizer is combined with the application of humic substances (HS). However, these beneficial effects are inconsistent and can depend on the type of soil. This study was performed to evaluate the effects of the application of HS (0, 1.25, and 7.50 mL pot–1), as Humic HF®, and fertilizer-P (10, 50, 100, and 200 mg P dm–3), as triple superphosphate, on root morphological characteristics, dry matter accumulation, nutrient uptake, and tuber yield of potatoes grown in sandy and clayey soils. Only under low P supply in the sandy soil did the supply of HS, at the rate of 1.25 mL pot–1, increase the plant growth, yield of tubers, and uptake of macronutrients by the plants, without affecting the efficiency of the P fertilization. In the clayey soil, which had a higher organic matter content, the application of HS did not affect plant growth, tuber yield or nutrient uptake. In both soils, P fertilization increased plant growth, tuber yield, and nutrient uptake. The combined application of HS and P increased the root length of potatoes in sandy soil. [ABSTRACT FROM AUTHOR]

As the typical organic matter, humic acids (HAs) were studied to explore its effect on the degradation of tetrabromobisphenol A (TBBPA) in anaerobic co-metabolic biodegradation systems. The highest degradation rate (86.9%) and lowest half-life (19.66 h) for TBBPA were obtained in the C-HA-T system (anaerobic co-metabolic reactor with glucose–HA/TBBPA as substrate), which illustrated that the efficiency of the biodegradation of TBBPA was improved due to the addition of HA. The 1,3-dibromo-2-methoxy-5-(2-(p-tolyloxy)propan-2-yl) benzene and 2,6-dibromo-4-(prop-1-en-2-yl)phenyl acetate were detected as the intermediate metabolites of TBBPA, which can conclude that HA has changed the biodegradation pathway of TBBPA. Further, the analysis of microbial diversity showed that Azoarcus was most likely responsible for the biodegradation of TBBPA in C-HA-T. [ABSTRACT FROM AUTHOR]

This study was conducted in the farmer field between the years 2014 and 2015. In this study, 3 doses of potassium (K) (0, 10, and 20 kg da−1) of K2SO4 (50% K2O) fertilizer and 3 doses of humic acid (HA) (0, 20, and 40 kg da−1) (85% HA) were used. Increase in the HA dose reflected significant effects on pH, salt, organic matter, phosphorus, magnesium, iron, and manganese contents of the experiment area at p <.01 level. It was determined that increased potassium applications affected the salt, magnesium (Mg), iron (Fe), and copper (Cu) contents at p <.01 level. Increased HA application on plant growth criteria had a significant effect on biological yield, grain yield, and harvest index (p <.01). However, K did not reflect any effect on the growth stage of wheat. Increased number of HA applications on grain and straw nutrient content were found to have significant (p <.01) effects on P, K, Ca, Mg, Fe, and Zn. Increased potassium applications had an effect on the P, K, Mg, Fe, and Zn contents with a significant level (p <.01). It was observed that HA applications were more effective than potassium applications on both general soil properties and yield and nutrient content. [ABSTRACT FROM AUTHOR]

The use of vermicompost water extracts (teas) in horticulture to increase plant growth and yield and suppress pests and diseases, is well documented. However, its utilization and effects in hydroponics systems are unknown. Low concentrations of vermicompost teas, produced from food wastes, at rates of 1.6% and 3.2% for lettuce and 0.14%, 0.28% and 0.56% for tomatoes were investigated as additive and supplement in static hydroponic systems. Vermicompost teas significantly increased lettuce yields when concentrations of nutrient solutions were reduced to 25% and 50% of the recommended full rate for nutrient solutions compared to treatments without vermicompost teas. Even lower concentrations of vermicompost teas increased tomato yields significantly as a supplement in reduced nutrient solutions of 50%. The presence of a combination of trace amounts of plant hormones such as auxins, cytokinins, gibberellins and humic acids in vermicomposts teas are likely the responsible factor that increased yields of lettuce and tomato in static hydroponics systems with lower concentrations of nutrient solutions. [ABSTRACT FROM AUTHOR]

Guava is an important fruit species but poorly studied for the effect of humic substances and soil mulching on its nutrition and fruit production. Thus, an experiment was conducted to evaluate the nutritional status and fruit production of guava as a function of humic substances and soil mulching in Brazilian semiarid. The experimental design was in randomized blocks with treatments distributed in a factorial arrangement (5 × 2) referring to humic substances doses (0, 10, 20, 30 and 40 mL of Humitec plant−1) and organic mulching (with and without organic mulching). Nutritional status of guava is affected by humic substances and soil mulching. The use of humic substances combined with soil mulching promotes optimum supplies of nitrogen, phosphorus, calcium, sulfur, boron and iron, but not calcium, copper and zinc. Under sandy soil and semiarid climate it is possible to recommend 40 mL L−1 of humic substances and soil mulching. [ABSTRACT FROM AUTHOR]

In the current study, humic acids ultrafiltration was explored using spinning basket membrane module at different transmembrane pressure drops (207, 276, 345, and 414 kPa), rotational speeds (10.47, 20.99, 31.41, 52.36, and 73.30 rad s−1) and different concentration of HAs (50, 150, and 250 mg L−1). The internal pore blocking characteristics was investigated using modified Hermia’s pore clogging models like complete, standard, intermediate pore blocking, and the cake filtration model. After ultrafiltration of 50 mg L−1 solution, the cleaning process of fouled membrane was carried out using a system inbuilt back rotation of the membrane basket (10.47-52.36 rad s−1) and compared with the effect of ultrasonication (ultrasound power: 120 W, frequency: 50 kHz) for the same fouled membrane at the different sonication time interval (5-25 min). The maximum cleaning efficiency of 88% was observed at 25 min of ultrasonication of fouled membrane. [ABSTRACT FROM AUTHOR]

This study evaluates heavy metal removal associated with phytomass management in a Typic Hapludox after three applications of pig slurry. Like humic acids in pig slurry were characterized through physics and chemical spectroscopy technics. Heavy metal levels were determined in ration that was offered to pigs, anaerobically digested pig slurry, and plant tissues from pig slurry-fertilized black oat (Avena strigosaSchreb.) and ryegrass (Lolium multiflorumLam.) intercrop. Soil contamination was evaluated by the pseudo-total heavy metal levels in six soil layers and the bioavailable levels in the top soil layer. Results indicate that the ration is the origin of heavy metals in the pig slurry. The approximate levels in the ration were as follows (mg kg−1): Cu 23.9, Zn 92.02, 153.15, Mn 30.98, Ni 0.23, Pb 10.75, Cr 0.34, Co 0.08, and Cd 0.05. The approximate levels of these metals in the pig slurry were as follows (mg kg−1): Cu 71.08, Zn 345.67, Fe 83.02, Mn 81.71, Ni 1.13, Pb 4.35, Co 0.28, and Cd 0.16. Like humic acids contained 55% aliphatic chains, 14% oxygenated aliphatic chains, and 15% carboxyls, demonstrating their high capacity for interaction with heavy metals by forming soluble complexes. Soil contamination was indicated by the accumulation of heavy metals in the six soil layers in relation to the applied pig slurry dose (ranged as follows (mg kg−1): Cu 110 to 150, Zn 50 to 120, Ni 20 to 40, and Pb 12 to 16) and as bioavailable forms (levels ranged as follows (mg kg−1): Cu < 1, Zn 1.0–1.5, Ni 0.1–1.5, and Pb 1.9–6.3). The positive correlation between heavy metal accumulation in the plants and soil bioavailable heavy metal levels and the lowest heavy metal levels under higher intensity of phytomass removal demonstrate the ability of phytomass management to reduce soil contamination. [ABSTRACT FROM AUTHOR]

Extract and analysis of the Dissolved Organic Carbon (DOC) fractions were analyzed from the leachate of an uncontrolled dumpsite at Gohagoda, Sri Lanka. DOC fractions, humic acid (HA), fulvic acid (FA) and the hydrophilic (Hyd) fractions were isolated and purified with the resin techniques. Spectroscopic techniques and elemental analysis were performed to characterize DOCs. Maximum TOC and DOC values recorded were 56,955 and 28,493 mg/L, respectively. Based on the total amount of DOC fractionation, Hyd dominated accounting for ∼60%, and HA and FA constituted ∼22% and ∼17%, respectively, exhibiting the mature phase of the dumpsite. The elemental analysis of DOCs revealed carbon variation following HA > FA > Hyd, while hydrogen and nitrogen were similar in each fraction. The N/C ratio for HA was recorded as 0.18, following a similar trend in old dumpsite leachate elsewhere. The O/C ratios for HA and FA were recorded higher as much as 1.0 and 9.3, respectively, indicating high degree of carbon mineralization in the leachates. High content of carboxylic, phenolic and lactone groups in all DOCs was observed disclosing their potential for toxic substances transportation. The results strongly suggest the risk associated with DOCs in dumpsite leachate to the aquatic and terrestrial environment. [ABSTRACT FROM AUTHOR]

A column-based continuous elution (CCE) method was developed for extracting humic acids (HA) from vermicomposted organic waste. Dissolution of HA by passing extractant (0.2 M NaOH) through vermicompost in a column followed by elution under gravity resulted in yields of 47.5% and 74.7% extractable HA in 24 h by International Humic Substance Society (IHSS) method and CCE method, respectively. These results were 63.3% and 97.9% in 48 h, respectively. The extracted HA showed similar FTIR absorption spectra and chemical compositions. Rate of oxidative degradation of HA during extraction by the CCE method was lower as compared with the IHSS method indicating improvement in extraction without altering the quality. [ABSTRACT FROM AUTHOR]

This work investigated the catalytic ozonation of humic acids extracted from landfill leachate in the presence of CeO2/AC with focus on the kinetics of humic acids degradation. It was confirmed that the degradation of humic acids mainly took place in the solution bulk. The direct and indirect reaction constants of ozone against humic acids were determined. By analyzing the contributions of direct ozone oxidation and indirect •OH radicals oxidation to humic acids removal, it was found that •OH radicals oxidation predominated at all pH, indicating that the catalytic ozonation of humic acids with CeO2/AC involved •OH radicals mechanism. [ABSTRACT FROM PUBLISHER]

The effect of the continuous application of an organic amendment (OA) on the accumulation and composition of humic acids (HAs) in various upland field soils was analyzed using a fractional precipitation technique. Fractionation patterns of HAs from plots treated with farmyard manure (FYM) or composted rice straw plus chemical fertilizer (CF) and from plots treated with CF alone were obtained by the step-wise addition of ethanol, 200–800 mL L−1, to HAs dissolved in 0.01 M sodium hydroxide (NaOH), and their degrees of humification were compared. HAs with a higher degree of humification precipitated in more dilute ethanol concentrations. The largest distribution shifted to a fraction that precipitated at a lower ethanol concentration with increasing degree of humification of bulk HAs, without an accompanying decrease in the amount of fractions with lower degrees of humification. A continuous OA application resulted in larger HA fractions with lower degrees of humification in most of the fields. The progression of humification in OA-derived HAs and interactions with indigenous soil HAs were also suggested from the fractionation patterns. The structural properties of the sub-fractions were evaluated using Miyagi soil (Cambisol) HAs. High performance size exclusion chromatography indicated that the larger molecular size molecules tended to precipitate at lower ethanol concentrations. The contribution of FYM-derived materials to the FYM+CF plot HA sub-fractions was suggested by a larger distribution of larger molecular size molecules compared to the corresponding HA sub-fractions from the CF plot soil.13C cross polarization/magic angle spinning nuclear magnetic resonance analysis indicated that the fractions that precipitated at lower ethanol concentrations had more aromatic characteristics than the fractions that precipitated at higher ethanol concentrations and were soluble in 800 mL L−1ethanol. These samples were characterized by a high alkyl carbon (C) content and intense signals corresponding to methoxyl and phenolic C. A correlation analysis for the HA sub-fractions both from the FYM+CF and CF plots indicated that their degree of humification corresponds to the composition of C functional groups. [ABSTRACT FROM PUBLISHER]

No-tillage methods can help to reduce expenditures and improve profitability of the agricultural production. This issue has been widely discussed for the cultivation of many species, but there are no data on the subject concerning oilseed flax. The field experiments were conducted in the years that vary widely in the course of temperature and precipitation. Tillage method significantly affected the yield of flax in the interaction with the weather conditions. In the dry year, the cultivation method did not differentiate the flax yield, while in the optimum moisture year no-till resulted in a reduction of yield compared to conventional tillage. Weed control with herbicide has contributed to increased yield of linseed but the level of increase was higher with no-till compared to conventional cultivation. The number and weight of weeds in no-tillage flax was 50% lower comparing to conventional plowing in both variants of weed control. Weed control decreased the number and weight of weeds also by 50% regardless of cultivation method applied. Cultivation systems affect the size and composition of the soil microbial populations. No-tillage contributed to an increase of humic substances content in the soil environment, the quantity of soil bacteria, and the population structure. [ABSTRACT FROM PUBLISHER]

Humic substances can mediate electron transfer between microorganisms and Fe(III) minerals. Because it is unknown which microorganisms reduce humics in anoxic aquifers, we analyzed the diversity and physiological flexibility of Fe(III)-, humics-, and AQDS-reducers, which were present at up to 106 cells g−1. No significant differences in 16S rRNA gene based diversity were found between enrichment cultures reducing ferrihydrite, humics or AQDS. Even after repeated transfers many of the enrichments retained the ability to switch to other electron acceptors. This suggests that humics- and Fe(III)-reducing microorganisms in anoxic aquifers are rather versatile and able to reduce different extracellular electron acceptors. [ABSTRACT FROM PUBLISHER]

This laboratory study demonstrated the effectiveness of UV-H2O2on the disinfection of water contaminated with microorganisms and organic matter. It was shown that UV-H2O2has a higher efficiency than UV or hydrogen peroxide treatments applied alone. Performances were evaluated via microbiological and chemical parameters analyzed on both, water and biofilms (ATP, culturable and total bacteria, DOC and TOC). The optimization phases of the treatment confirmed a bacterial adaptation to H2O2when applied alone. This adaptation was not observed in the case of UV-H2O2. [ABSTRACT FROM AUTHOR]

This paper reports on the synthesis of spherical silver nanoparticles and the consequent formation of self-assembled humic-silver supramolecules. The method described in this article is eco-friendly and the supramolecules formed were stable for several months. The silver nanoparticles themselves were synthesised from humic acid extracted from mudbank sediments (from Aleppey, south west coast of India) and characterised by UV-Vis spectra and HRTEM. Tuning of dipole and quadrouple oscillation of spherical nanoparticles was achieved. Variable self-assembled distribution mechanism of humic-silver nanoparticles in the solution responsible for quadrouple intensification was investigated. [ABSTRACT FROM AUTHOR]

The effect of ozone dose on algae (Microcystic aeruginosa), algal extracellular organic matters (EOM), humic acids (HA) and four model compounds: bovine serum albumin (BSA), starch, deoxyribonucleic acid (DNA) and fish oil as precursors for disinfection by-products (DBPs) production was investigated. Algae showed the highest DBPs formation (71.8 μg mg−1total organic carbon (TOC)) than other samples. Only BSA showed lower chloroform yield (5.9 μg mg−1TOC) than haloacetic acids, HAAs (11.2 μg mg−1TOC). Algae, EOM, starch, DNA, fish oil and HA all showed higher chloroform yields (46.1, 23.8, 8.9, 37.1, 44.0 and 33.7 μg mg−1TOC, respectively) than HAAs (25.7, 20.2, 6.3, 10.0, 13.1 and 18.4 μg mg−1TOC, respectively). Pre-ozonation increased DBPs, especially chloroform, formation from algae and DNA significantly. With the increase in ozone doses, DBPs yields of algae and DNA increased 19.0 and 34.5 μg mg−1TOC, chloroform yields of algae and DNA increased 15.3 and 30.4 μg mg−1TOC, respectively. However, pre-ozonation decreased DBPs formation from starch, fish oil and HA, and the corresponding decrease amount was 2.4, 26.9 and 9.5 μg mg−1TOC, respectively. There are no regular change trends of DBPs formation from EOM and BSA with the increase in ozone doses. [ABSTRACT FROM PUBLISHER]

Dicamba is one of herbicides used widely in agriculture today. The wide use of dicamba in agriculture represents a potential danger to the ecosystems and the environment. Thus, the present study is aimed to investigate the DNA damage levels and the DNA methylation changes inPhaseolus vulgarissubjected to whether dicamba and humic acids (HAs) have any protective effect on these changes. Randomly Amplified Polymorphic DNAs (RAPDs) and Coupled Restriction Enzyme Digestion-Random Amplification (CRED-RAs) were used to determinate the DNA damage levels and the changes in the pattern of DNA methylation. The results showed that dicamba (0.2, 0.4 and 0.6 ppm) caused RAPDs profile changes (DNA damage) as increasing, genomic template stability (GTS) as decreasing and DNA hypomethylation. However, these effects of dicamba seen at higher levels decreased after treatment with five different concentrations (2, 4, 6, 8 and10%) of HAs. The results of this experiment have clearly shown that HAs could be used effectively to protect bean seedlings from the destructive effects of dicamba. [ABSTRACT FROM AUTHOR]

Humic substances (HS) and preparations created on their basis are known to be effective in growth stimulation and improvement of resistance and productivity of different plant species. We have revealed that the presowing semidry treatment of wheat seeds with preparation HUMI (NVP 'BashIncom', Ufa, Bashkortostan, Russia) promoted seedling growth and increased wheat yield. This effect is likely to be due to the shifts induced by HUMI in the hormonal system of plants associated with a 1.5-fold persistent accumulation of cytokinins (CKs) without any changes in the contents of indoleacetic acid (IAA) and abscisic acid (ABA). Meanwhile, presowing treatment with HUMI had a stabilizing effect on the state of the hormonal system in the course of ontogenesis of wheat inoculated with teliospores Tilletia caries. Obtained data about prevention of the decline in the cytokinin content in HUMI-treated infected wheat is fundamental in the implementation of immuno-stimulatory effect of HUMI resulting in the suppression of the growth and development of pathogens. [ABSTRACT FROM AUTHOR]

The objective of this study is to analyze soil hydrophysical properties in addition to the molecular composition of the organic matter in semiarid Mediterranean cereal agroecosystems. Aggregate water-stability, total porosity, water holding capacity, andbandcparameters of the Kostiakov's equation for soil infiltration were determined using a double-ring infiltrometer. The soil humic acid (HA) was isolated and characterized mainly by analytical pyrolysis-gas chromatography mass spectrometry. Multivariate data treatments suggested favourable hydrophysical parameters associated to HAs with a substantial aliphatic domain. Soils with HAs consisting of condensed aromatic structures, often considered to correspond to advanced stages of humification and high resilience, do not coincide with those displaying favourable hydrophysical properties. The results discussed in this article provide support for moderate aliphatic hydrophobicity to be considered as a soil organic matter quality parameter positively influencing hydrophysical properties of semiarid soils. [ABSTRACT FROM PUBLISHER]

Real-time PCR for the quantitative assessment of microbial genes in DNA extracted from environmental samples is increasingly being used in microbial ecology studies. A significant problem with the quantitative aspect of the method is the possible inhibition of the PCR process by humic substances co-extracted with the DNA. A comparison of the inhibition exerted by five structurally different humic substances on six commercially available DNA polymerases revealed large differences in the resistance of the polymerases to inhibition. Depending on the DNA polymerases (or their formulation) the addition of Bovine Serum Albumin (BSA) to the mastermix reaction generally increased the resistance to the different humic substances and decreased differences between the polymerases. One of the tested polymerases was clearly hampered by the addition of BSA, indicating that BSA cannot be added to just any mastermix to improve enzyme performance. The structural differences in the tested humic acids suggest that the mechanism of the inhibition is not a feature of all organic structures, but mainly related to the presence of certain phenolic or quinonoid structures. [ABSTRACT FROM PUBLISHER]

A laboratory incubation study was conducted to examine the effects of exogenous humic acids on the forms of organic phosphorus (P) in three contrasting soil types: red soil, brown soil, and drab soil. Results indicated that the Olsen P concentration increased in all the three types of soil with addition of the humic acid extracts, with the magnitude of increment ranked in a sequence of brown soil > drab soil > red soil. For the soil organic P fractions, addition of the humic acid extracts increased the labile organic P and moderately labile organic P concentrations while reducing the moderately resistant organic P and highly resistant organic P concentrations, suggesting that the exogenous humic acids could enhance transformation of organic P from resistant forms to labile forms. The activation of organic P by addition of the humic acid extracts varied with soil type, and this variation was related to soil characteristics. [ABSTRACT FROM PUBLISHER]

Compost stability assessment within different particle size fractions was studied. Humic acids (HAs) were extracted from two kinds of co-composts prepared using evaporated olive mill wastewater (OMSW) or solid waste from olive oil extraction (OC) and poultry manure (PM). The elemental composition, Fourier-transform infrared spectroscopy (FTIR) and13C-NMR (nuclear magnetic resonance) analysis and molecular weight distribution were investigated to assess the composted organic matter stability in different fractions. In both composts, organic matter content was higher in the>2 mm fractions than in the<2 mm fractions, because of fractions’ richness in hardly biodegradable compounds. Spectroscopic analysis revealed that OMSW compost fraction<2 mm and OC compost 2–4 mm fraction were rich in aromatic compounds and oxygenated groups but poor in aliphatic structure. Moreover, the HA distribution reflected a high stabilized compost<2 mm fraction, especially from evaporated effluent known as phytotoxic. However, the 4–6 mm fraction included high aliphatic compounds besides aromatic structures and did not exhibit any phytotoxicity, confirming compost fraction maturity. However, the low C/N ratio, the high OMSW compost mineral nutritive elements and the high aromatic C rate reflected highly stabilized products. Consequently, the performance of both prepared organic fertilizers for agriculture use contested the previous negative effect ascribed to olive mill wastewater. [ABSTRACT FROM AUTHOR]

To investigate the chemical heterogeneity of humic acids (HAs), we applied two-dimensional (2-D) electrophoresis to HAs from a compost and two types of soils. In this method, HAs are first separated by isoelectric focusing (IEF) and then separated by polyacrylamide gel electrophoresis (PAGE). IEF and PAGE were carried out in the presence of 7 M urea. Upon 2-D electrophoresis of HAs, dark-colored substances were spread out across the gel mainly in the isoelectric point (pI) range of 3.0–4.5. Green fluorescence was observed in the smaller molecular size region of the gel, especially in the pI range of 3.0–4.5, and the most intense fluorescence was found at the moving front. The gels were divided into 36 sections, and then HA constituents were extracted from the individual sections and recovered by precipitation with acid. The distribution of organic carbon (C) among the gel sections coincided with that of the dark-colored substances on the gel. The total C recoveries were only 43–50%, suggesting that a considerable amount of HA constituents was lost during the extraction from the gels and purification. High-performance size-exclusion chromatography confirmed that the constituents of HAs were separated based on their molecular sizes by PAGE. The measurement of diffuse reflectance infrared Fourier transform (DRIFT) spectra indicated that the chemical properties of the HA constituents differed depending on the position on the gels and were affected by the molecular size rather than the pI. The fractions of the compost HA were characterized by higher proportions of aliphatic, proteinous and polysaccharide moieties and by the presence of lignin-derived structures. For the soil HAs, the fractions were characterized by a high proportion of the carboxyl group and a low proportion of aliphatic moieties. The proportion of proteinous and polysaccharide moieties in the fractions of soil HAs decreased with decreasing molecular size. The chemical properties of the green fluorescent substances remained unclear, since there was not enough of the substances to measure the DRIFT spectra. The present study showed that 2-D electrophoresis in the presence of concentrated urea offers an effective method for fractionating and isolating the constituents of HAs. [ABSTRACT FROM PUBLISHER]

In the present work, we study the effects that aggregation of humic acids in seawater, and its adsorption to surfaces, can have on the determination of Cu and Pb accumulation by phytoplankton within the context of metal bioavailability studies, using the diatom Thalassiosira weissflogii. Two methods commonly used for collection of algae to analyse metal content, filtration and centrifugation, were compared, and a procedure to differentiate the metal internalized by the alga from that adsorbed to cell walls-washing with 0.01 M ethylenediaminetetraacetic acid (EDTA)- was optimized for its use in seawater and in the presence of humic acids. The present results highlight the possibility of obtaining biased results if filtration is used to isolate the algae, and show that centrifugation is a more suitable procedure minimizing contribution of particulate and colloidal forms of metals to the measured cellular and intracellular metal contents. Thus a combination of centrifugation to isolate the algae from the medium with a 10 minutes washing with a washing agent composed of EDTA 0.01 M at pH 8 and NaCl and KCl to 0.5 M ionic strength is recommended to extract metals adsorbed to the surfaces of marine phytoplankton for a seawater containing humic substances. The importance of discriminating between internalized metal and total cellular metal in bioavailability studies is noted, given the different effects of humic substances on metal accumulation in the different cellular pools. [ABSTRACT FROM AUTHOR]

We investigated soil organic matter in a forest of natural Hinoki cypress ( Chamaecyparis obtusa) under perhumid weather conditions in north central Taiwan. Humic substances along the transect from the summit and footslope to lakeshore were characterized by use of solid-state cross-polarization, magic-angle-spinning C nuclear magnetic resonance spectroscopy (CP/MAS C-NMR). The major components of soil organic carbon in whole soil and humic substances were alkyl-C, O-alkyl-C, and di- O-alkyl-C, ranging from 60.6% to 80.7%, then aromatic-C, 7.5% to 9.8%. The degree of humification of soil organic matter, both O-alkyl-C/alkyl-C ratio and aromaticity, decreased slightly from the summit to lakeshore. The content of functional groups of polar and acidic groups, including O-alkyl-C, di- O-alkyl-C, and carboxyl-C, corresponded with the topographical effect, increasing slightly from the summit to lakeshore. However, the relatively low degree of humification in soils of this perhumid forest and low aromaticity were due to high precipitation and acidity, which appeared to hinder organic matter decomposition with topography change. [ABSTRACT FROM AUTHOR]

Meat processing grease wastes were composted with lignocellulosic material. Judging by the reduction in the yield of compost lipophilic extract, grease was degraded during the first 20 days of composting. Compost humic acids (HA) and fulvic acids (FA) were characterized by elemental analysis, Fourier transform infrared (FT-IR) spectroscopy and analytical pyrolysis. The compost HA and FA fractions contained a ligno-protein complex. The presence of grease (6.7% dry weight) during composting had a slight influence on the chemical composition of HA and FA. Analytical pyrolysis indicated that, during composting, major changes were observed in the FA fraction, namely, the proportion of nitrogen-bearing compounds increased and carbohydrate-derived products decreased drastically in the final compost. In addition, the shortening of the aliphatic chains of lignin-derived compounds was observed with an increase in the C6C(0−2)/C6C3 ratio in pyrolysates. [ABSTRACT FROM PUBLISHER]

The aim of the present study was to investigate tebuconazole sorption on common soil minerals (birnessite, ferrihydrite, goethite, calcite and illite) and humic acids (representing soil organic matter). Tebuconazole was used (i) in the commercial form Horizon 250 EW and (ii) as an analytical grade pure chemical. In the experiment with the commercially available tebuconazole, a significant pH-dependent sorption onto the oxides was observed (decreasing sorption with increasing pH). The highest sorption was found for ferrihydrite due to its high specific surface area, followed by humic acids, birnessite, goethite and illite. No detectable sorption was found for calcite. The sorption of analytical grade tebuconazole on all selected minerals was significantly lower compared to the commercial product. The sorption was the highest for humic acids, followed by ferrihydrite and illite and almost negligible for goethite and birnessite without any pH dependence. Again, no sorption was observed for calcite. The differences in sorption of the commercially available and analytical grade tebuconazole can be attributed to the additives (e.g., solvents) present in the commercial product. This work proved the importance of soil mineralogy and composition of the commercially available pesticides on the behavior of tebuconazole in soils. [ABSTRACT FROM PUBLISHER]

Humic substances constitute an important part of persistent organic matter in natural waters. This study focuses on standard humic acid (HA) degradation by UV irradiation alone and combined with H2O2. At high concentration, chloride is known to be a radical scavenger that could affect humic acid degradation by photochemical processes. The influences of pH, NaCl presence and H2O2 concentration are discussed here. UV irradiation shows a slight HA degradation but addition of H2O2 greatly improved aromatics removal. Higher the pH and higher the H2O2 dose, more HA is degraded. In chloride ion presence, HA degradation is reduced that confirms chloride scavenging effect. Also, high ionic strength impacts on HA molecular configuration limiting its degradation. [ABSTRACT FROM AUTHOR]

This work aimed to characterize the coagulant properties of protein preparations from Moringa oleifera seeds in the removal of humic acids from water. Three distinct preparations were assayed, namely extract (seeds homogenized with 0.15 M NaCl), fraction (extract precipitated with 60% w/v ammonium sulphate) and cMoL (protein purified with guar gel column chromatography). The extract showed the highest coagulant activity in a protein concentration between 1 mg/L and 180 mg/L at pH 7.0. The zeta potential of the extract (−10 mV to−15 mV) was less negative than that of the humic acid (−41 mV to−42 mV) in a pH range between 5.0 and 8.0; thus, the mechanism that might be involved in this coagulation activity is adsorption and neutralization of charges. Reduction of total organic carbon (TOC) and dissolved organic carbon (DOC) was observed in water samples containing 9 mg/L carbon as humic acid when treated with 1 mg/L of the extract. A decrease in colour and in the aromatic content of the treated water was also observed. These results suggested that the extract from M. oleifera seeds in a low concentration (1 mg/L) can be an interesting natural alternative for removing humic acid from water in developing countries. The extract dose determined in the present study does not impart odour or colour to the treated water. [ABSTRACT FROM PUBLISHER]

The adsorption of two acidic pharmaceutically active compounds (PhACs), clofibric acid and ketoprofen, onto powdered activated carbon (PAC) was investigated with a particular focus on the influence of natural organic matter (NOM) on the adsorption of the PhACs. Suwannee River humic acids (SRHAs) were used as a substitute for NOM. Batch adsorption experiments were conducted to obtain adsorption kinetics and adsorption isotherms with and without SRHAs in the system. The adsorption isotherms and adsorption kinetics showed that the adsorption of clofibric acid was not significantly affected by the presence of SRHAs at a concentration of 5 mg (as carbon) L−1. An adsorption capacity of 70 to 140 mg g−1 was observed and equilibrium was reached within 48 h. In contrast, the adsorption of ketoprofen was markedly decreased (from about 120 mg g−1 to 70–100 mg g−1) in the presence of SRHAs. Higher initial concentrations of clofibric acid than ketoprofen during testing may explain the different behaviours that were observed. Also, the more hydrophobic ketoprofen molecules may have less affinity for PAC when humic acids (which are hydrophilic) are present. The possible intermolecular forces that could account for the different behaviour of clofibric acid and ketoprofen adsorption onto PAC are discussed. In particular, the relevance of electrostatic forces, electron donor-acceptor interaction, hydrogen bonding and London dispersion forces are discussed [ABSTRACT FROM PUBLISHER]

A simple, reliable and novel solid phase extraction procedure using the Empore™ chelating disk has been developed for determination of Tl(I) and Tl(III) in environmental water samples by electrothermal atomic absorption spectrometry (ETAAS). The influence of humic acids on separation/preconcentration of thallium species with the Empore™ chelating disk is investigated. The preconcentration factor and detection limit are 500 and 5 ng L-1, respectively. The recoveries are in the range 93-103% for mineral, pond, sea, snowmelt, waste waters at 28-500 ng L-1 Tl and in the range 82-112% for river waters at 18-28 ng L-1 Tl. [ABSTRACT FROM AUTHOR]

The formation of PGE-humic acid (HA) complexes in soil and street dust samples was investigated. In order to assess the distribution of Pt and Pd among molecular weight fractions of humic substances, the HA extracts (extracted by 0.1 mol L-1 sodium pyrophosphate) were analysed by size exclusion chromatography coupled on-line with UV-Vis detection. Similar chromatograms were obtained for soils and street dust samples (254 nm, 280 nm) and two size fractions were operationally defined as high (1600-5000 Da) and low molecular (< 1600 Da) HA fractions. The concentration of Pt and Pd in the separated extracts was determined by ICP-MS. The results indicate that up to 43% of Pt is in the high molecular and up to 52% in the low molecular HA fraction. In both type of soil samples, Pd is preferentially bound to the low molecular HA fraction. Dependence of Pd-HA and Pt-HA formation on the sample type both in the soils and in the street dust sample as well as on Pt oxidation state was established. Metallic Pt shows a tendency for complexation with the fractions of HA higher than 5000 Da. In the street dust samples, the distribution of Pt and Pd is similar and is strongly dependent on the sample type, being bound mainly to the fractions: higher than 5000 Da, 1600-5000 Da and the fraction lower than 1600 Da. [ABSTRACT FROM AUTHOR]

Natural organic matter (NOM) plays an important role in many environmentally relevant processes. NOM includes many different types of compounds, not all of which behave similarly. Much effort has gone into characterising some fractions of NOM (e.g. humic substances) in the different environmental compartments, in finding tracers to ascertain their origin, etc. However, few methods exist for quantifying the different types of NOM and, as a result, field studies have limited themselves to measuring only total or dissolved organic carbon. In this article, the few existing methods for humic substance quantification are reviewed, and the implications of the current lack of simple measurement methods are discussed in relation to two fields of high environmental relevance: trace element speciation modelling and natural colloid and engineered nanoparticle fate. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the effect of the size of the soil particle containing organic matter, the type of organic fertiliser (cattle manure, vermicompost, straw) and the decomposition time of these fertilisers in soil on the hydrophilic-hydrophobic properties and polydispersity of humic acid molecules. In the model incubation experiment, organic fertilisers (cattle manure, vermicompost and wheat straw) were mixed with soil material (sandy texture). The soil was sampled for testing after one and three years of incubation. Each sample was separated into two fractions according to graining, grain diameter>0.1 mm (sand fraction) and<0.1 mm (silt and clay fraction), and humic acids (HAs) were isolated. For the HAs isolated, hydrophilic-hydrophobic properties were defined using RP-HPLC, and the division was made into low- and high-molecular-mass fractions (HPSEC). It was demonstrated that introducing organic fertilisers into soil resulted in an increase in the proportion of hydrophobic and high-molecular mass fractions and a decrease in the proportion of hydrophilic and low-molecular mass fractions in the HA molecules. Highest values for the ratio HIL/ΣHOB and lowest values for S1/S2 were noted for HAs of soil mixed with straw. HAs isolated from the fine-grained soil fraction demonstrated a higher degree of 'maturity' than HAs from the coarse-grained fraction, which was seen as higher values for HIL/ΣHOB and lower values for S1/S2. [ABSTRACT FROM AUTHOR]

Humic acid (HA) characteristics were studied in a natural revegetation chronosequence of 10-, 20-, 60-year-old and mature podzol soils under a pine forest, along the spoil heaps of a sand quarry. The elemental composition of HAs showed a trend towards carbon increase and hydrogen decrease with soil age. Essential differences in the atomic ratios between humic acids extracted from the different soils may be due to the intensity of the humification process as related to soil age. Compared with HAs extracted from organic horizons, those from mineral horizons showed lower C/N and H/C ratios, whereas O/C ratios were higher. Electrophoretic data showed that the proportion of the more-mobile fraction (L-MS) was higher in the mineral horizons than in the organic horizons and, among organic layers, in the Oe and Oa horizons compared with Oi. Intensive transformation of pine remains may have occurred and led to HAs with an increasing degree of humification in only 60 years. Moreover, progressive accumulation of the L-MS fraction in the E and Bs horizons with soil age might be the result of the ongoing migration of the most-polar organic compounds down through the soil profiles. [ABSTRACT FROM AUTHOR]

We studied, under laboratory conditions, the effects of Nostoc 9v (cyanobacteria) on the soil organic matter (SOM) content and quality of different soils from Tanzania, Zimbabwe, and South Africa. Soils were inoculated with Nostoc 9v at a rate of 5 mg dry biomass g-1 soil and incubated for 3 months at 27°C under 22 W m-2 illumination for 16 h and 8 h under darkness. Moisture content was maintained at 60% of field capacity. The composition of the SOM and the structural features of the humic acid (HA) fraction were studied by visible and infrared (IR) spectroscopies. Nostoc 9v proliferated and colonized the surfaces of all soils very quickly. The results obtained showed significant changes in the quantitative and qualitative characteristics of the SOM due to cyanobacterial growth. Inoculation and further incubation with Nostoc 9v promoted increases in organic carbon (OC) that ranged from 0.4 g C kg-1 soil to 9.0 g C kg-1 soil. Cyanobacterial growth also affected SOM characteristics through the incorporation of free, extractable, or particulate biomass with a predominantly aliphatic character. Important descriptors of the extent to which cyanobacterial metabolism modified the characteristics of the native SOM were the changes in the observed amounts of the two humin types, the increase in lipid concentration, and the changes in the optical density of the HAs. [ABSTRACT FROM AUTHOR]

Humic acid formation and soil physical properties were studied in a Mediterranean calcimorphic vineyard after a 5-year application of wine vinasses. This treatment increased significantly (P < 0.05) soil carbon content (×3.7), humic acid (×6.8), aggregate stability (×3.5), water retention (×1.5), and permeability (×2.3) and decreased penetration resistance (×6.6). The humic acid infrared spectra in soils with wine vinasses showed enhanced protein (1640, 1540 cm-1) and aromatic (1620, 1510 cm-1) bands, suggesting rapid transformation of the water-soluble wine vinasses into melanoidin-like macromolecules. In the humic acid from untreated soils, lignin-derived structures prevailed. The second-derivative visible spectra of the humic acid showed peaks at 530, 570, and 620 nm produced by fungal-derived dihydroxyperylenequinones, the intensity of which increased with the distance in soil from the vinasses' application point. The immobilization and stabilization in soil of wine vinasses, a fairly biodegradable material, and its bearing in the local improvement of several soil properties are emphasized. [ABSTRACT FROM AUTHOR]

The present study deals with the application of ozone with perfluorooctylalumina in humic acids decomposition. Ozonation with perfluorooctylalumina addition destroys the complex structures in humic acids into relatively simple ones and color removal based on ADMI (American Dye Manufacture Index) measurement was greater than 95% in all tests. The rate of humic acids decomposition was described by using a first-order rate expression with respect to the decrease of A254. A central pH level (pH 7) and perfluorooctylalumina addition is helpful in humic acids decomposition. The modified-Nernst equation could be used to predict humic acids decomposition at varying reaction conditions. [ABSTRACT FROM AUTHOR]

The aim of this paper is to investigate the efficiency of a hybrid coagulation-microfiltration process for the removal of copper from a synthetic wastewater in comparison with the application of microfiltration alone. The wastewater samples contained various concentrations of humic acids, kaolin (clay), and Cu2+ ions in tap water. The effect of the concentrations of the constituents on the performance of microfiltration is examined. The efficiency of microfiltration was evaluated by measuring several parameters, including residual Cu2+ concentration, residual turbidity, residual humic acids concentration, pH, conductivity, and alkalinity. A conventional inorganic salt (Fe2(SO4)3) and a novel composite inorganic-organic coagulant (PFS-PAA) were applied as coagulation agents to further enhance the microfiltration efficiency. The results show that membrane microfiltration is very efficient in treating such wastewaters, while the hybrid process exhibits even better performance, when compared to microfiltration. [ABSTRACT FROM AUTHOR]

Photochemical behaviour of sethoxydim-lithium, a cyclohexanedione oxime herbicide, has been investigated in ultrapure and natural waters (mineral, well and river water). Photodegradation experiments were carried out under laboratory conditions using a solar silulator (Suntest equipment) and under natural solar irradiation in order to evaluate reaction kinetics of the active ingredient. Besides, the effect of humic acids (HA) on the degradation rate under simulated solar radiation was also studied. The photodegradation rates of sethoxydim-lithium in all the different waters and light sources studied followed first-order kinetics. Results showed that dark reactions were negligible. Experimental data showed that half-lives of the herbicide under simulated irradiation were higher in natural waters than in ultrapure, showing the lowest degradation rate in river water (t1/2 = 135.5 ± 0.3 min). Under natural sunlight, sethoxydim-lithium photodegradation followed the same behaviour, with half-lives that range from 82 to 437 min for ultrapure and river water respectively, showing a strong dependence on the composition of water. However, rates of degradation of sethoxydim-lithium were faster under simulated radiation compared to natural sunlight (e.g. t1/2 (ultrapure water) 59.8 ± 0.2 min vs. 82.1 ± 0.7 min). The presence of different concentrations of HA (1-20 mg L-1) retarded the photolytic degradation relative to ultrapure water with half-lives from 92 to 196 min. [ABSTRACT FROM AUTHOR]

Sorption of phenanthrene (Phen) and benzo[α]pyrene (BaP) by humic acids (HAs) extracted from four typical soils in China, including cinnamon soil, fluvo-aquic soil, red soil, and mountain meadow soil were investigated. All sorption data were fitted well by the Freundlich model, but BaP exhibited stronger and more nonlinear sorption than Phen by a given HA. For Phen isotherms, there was a positive relation between Koc values and aliphaticity of HAs, whereas a negative correlation was observed between n values and aliphaticity. This indicated the importance of aliphatic groups in Phen sorption capacity and nonlinearity. Compared to Phen, a similar trend was obtained between n values of BaP and aliphaticity or aromatic carbon. However, no correlation existed between Koc values for BaP and aliphaticity or aromatic carbon. [ABSTRACT FROM AUTHOR]

Previous study showed that nitrogen content in lignite humic acids (HA) increased significantly during lignite biodegradation. In this paper we evaluated the factors responsible for the increased level of N in HA and the formation of new nitrogen compound following microbial degradation. When the ammonium sulfate concentration in lignite medium was < 0.5%, the N-content in HA was higher than that in the crude lignite humic acid (cHA); when the ammonium sulfate concentration was ≥ 0.5%, both the biodegraded humic acid (bHA) N-content and the content of bHA in lignite increased significantly, but at 2.0% no increase was observed. This indicated that HA incorporated N existing in the lignite medium, and more HA can incorporate more N with the increase of bHA amount in lignite during microbial degradation. CP/MAS 15N NMR analysis showed that the N incorporated into HA during biotransformation was in the form of free or ionized NH2-groups in amino acids and sugars, as well as NH4+. We propose nitrogen can be incorporated into HA biotically and abiotically. The high N content bHA has a potential application in agriculture since N is essential for plant growth. [ABSTRACT FROM AUTHOR]